Set the smoker temperature to 225° F. Once smoker is ready, inject 2 ounces per pound of the smoking brine throughout the roast. Next, season the outside liberally with the roast beef seasoning. Place the roast on a rack in the Cajun Injector Electric Smoker. Spray with basting spray and pour apple juice into drip pan in smoker. Place ¼ cup of either the oak or pecan pellets in the wood tray and rotate to dump pellets into the element. Let the roast smoke for about 4-5 hours at 225 degrees F. Use the basting spray again about 2 hours into the smoking process. After four hours check internal temperature of the roast, it should be at 165 degrees F. When internal temperature is 165 degrees F, pull the roast off the smoker and apply the BBQ finishing sauce. Let roast sit for 15 minutes before carving.